OFFSET
1,1
COMMENTS
Primes p such that A140686(p) = 0. - Michael Somos, Feb 12 2011
Primes (along with 2) which cannot be written in the form a^2 + 7*b^2, where a > 0, b > 0. - V. Raman, Sep 08 2012
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 1..1000
MATHEMATICA
Select[Prime[Range[300]], MemberQ[{0, 3, 5, 6}, Mod[#, 7]]&] (* Vincenzo Librandi, Aug 12 2012 *)
PROG
(Magma) [ p: p in PrimesUpTo(600) | p mod 7 in {0, 3, 5, 6} ]; // Vincenzo Librandi, Aug 12 2012
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
STATUS
approved